Image sensors are used for a wide variety of applications such as digital still cameras, machine vision, automotive and gaming, etc. Most 2D image sensors have a readout block which is shared among multiple pixels (typically one column's worth). Hence it is not possible to read out multiple rows at a time and so the rows are read out in a sequential manner. As each pixel typically collects light for the same amount of time, the rows of the sensor are sequentially reset. (The time between a pixel's reset and a pixel's readout is its exposure, also known as integration time). If an object (or sensor) is moving during the readout, there will be artifacts due the sequential nature of the reset and readout. This is called rolling blade shutter artifacts, as they are similar to silver-halide film sensors and the mechanical shutter blades and their associated artifacts.
As a result of such artifacts, a different pixel design is sometimes employed in digital image sensors, namely “global shutter pixels”. In these types of pixels, there is a storage element inside the pixel. In a typical configuration, all pixels on the sensor are simultaneously reset, simultaneously exposed and then the signal information is simultaneously transferred to each pixels' respective storage. The storage pixels are then read out, typically row sequential. As all the pixels are exposed at the same time, there is no rolling blade shutter artifacts.
While avoiding rolling shutter blade artifacts is advantageous, further enhancements to global shutter pixel configurations may be desirable for certain applications.